gdb/language.h

   1 /* Source-language-related definitions for GDB.
   2
   3    Copyright (C) 1991-2019 Free Software Foundation, Inc.
   4
   5    Contributed by the Department of Computer Science at the State University
   6    of New York at Buffalo.
   7
   8    This file is part of GDB.
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  22
  23 #if !defined (LANGUAGE_H)
  24 #define LANGUAGE_H 1
  25
  26 #include "symtab.h"
  27 #include "common/function-view.h"
  28 #include "expression.h"
  29
  30 /* Forward decls for prototypes.  */
  31 struct value;
  32 struct objfile;
  33 struct frame_info;
  34 struct ui_file;
  35 struct value_print_options;
  36 struct type_print_options;
  37 struct lang_varobj_ops;
  38 struct parser_state;
  39 class compile_instance;
  40 struct completion_match_for_lcd;
  41 class innermost_block_tracker;
  42
  43 #define MAX_FORTRAN_DIMS  7     /* Maximum number of F77 array dims.  */
  44
  45 /* range_mode ==
  46    range_mode_auto:   range_check set automatically to default of language.
  47    range_mode_manual: range_check set manually by user.  */
  48
  49 extern enum range_mode
  50   {
  51     range_mode_auto, range_mode_manual
  52   }
  53 range_mode;
  54
  55 /* range_check ==
  56    range_check_on:    Ranges are checked in GDB expressions, producing errors.
  57    range_check_warn:  Ranges are checked, producing warnings.
  58    range_check_off:   Ranges are not checked in GDB expressions.  */
  59
  60 extern enum range_check
  61   {
  62     range_check_off, range_check_warn, range_check_on
  63   }
  64 range_check;
  65
  66 /* case_mode ==
  67    case_mode_auto:   case_sensitivity set upon selection of scope.
  68    case_mode_manual: case_sensitivity set only by user.  */
  69
  70 extern enum case_mode
  71   {
  72     case_mode_auto, case_mode_manual
  73   }
  74 case_mode;
  75
  76 /* array_ordering ==
  77    array_row_major:     Arrays are in row major order.
  78    array_column_major:  Arrays are in column major order.  */
  79
  80 extern enum array_ordering
  81   {
  82     array_row_major, array_column_major
  83   }
  84 array_ordering;
  85
  86
  87 /* case_sensitivity ==
  88    case_sensitive_on:   Case sensitivity in name matching is used.
  89    case_sensitive_off:  Case sensitivity in name matching is not used.  */
  90
  91 extern enum case_sensitivity
  92   {
  93     case_sensitive_on, case_sensitive_off
  94   }
  95 case_sensitivity;
  96
  97
  98 /* macro_expansion ==
  99    macro_expansion_no:  No macro expansion is available.
 100    macro_expansion_c:   C-like macro expansion is available.  */
 101
 102 enum macro_expansion
 103   {
 104     macro_expansion_no, macro_expansion_c
 105   };
 106
 107 \f
 108 /* Per architecture (OS/ABI) language information.  */
 109
 110 struct language_arch_info
 111 {
 112   /* Its primitive types.  This is a vector ended by a NULL pointer.
 113      These types can be specified by name in parsing types in
 114      expressions, regardless of whether the program being debugged
 115      actually defines such a type.  */
 116   struct type **primitive_type_vector;
 117
 118   /* Symbol wrappers around primitive_type_vector, so that the symbol lookup
 119      machinery can return them.  */
 120   struct symbol **primitive_type_symbols;
 121
 122   /* Type of elements of strings.  */
 123   struct type *string_char_type;
 124
 125   /* Symbol name of type to use as boolean type, if defined.  */
 126   const char *bool_type_symbol;
 127   /* Otherwise, this is the default boolean builtin type.  */
 128   struct type *bool_type_default;
 129 };
 130
 131 /* Structure tying together assorted information about a language.  */
 132
 133 struct language_defn
 134   {
 135     /* Name of the language.  */
 136
 137     const char *la_name;
 138
 139     /* Natural or official name of the language.  */
 140
 141     const char *la_natural_name;
 142
 143     /* its symtab language-enum (defs.h).  */
 144
 145     enum language la_language;
 146
 147     /* Default range checking.  */
 148
 149     enum range_check la_range_check;
 150
 151     /* Default case sensitivity.  */
 152     enum case_sensitivity la_case_sensitivity;
 153
 154     /* Multi-dimensional array ordering.  */
 155     enum array_ordering la_array_ordering;
 156
 157     /* Style of macro expansion, if any, supported by this language.  */
 158     enum macro_expansion la_macro_expansion;
 159
 160     /* A NULL-terminated array of file extensions for this language.
 161        The extension must include the ".", like ".c".  If this
 162        language doesn't need to provide any filename extensions, this
 163        may be NULL.  */
 164
 165     const char *const *la_filename_extensions;
 166
 167     /* Definitions related to expression printing, prefixifying, and
 168        dumping.  */
 169
 170     const struct exp_descriptor *la_exp_desc;
 171
 172     /* Parser function.  */
 173
 174     int (*la_parser) (struct parser_state *);
 175
 176     /* Given an expression *EXPP created by prefixifying the result of
 177        la_parser, perform any remaining processing necessary to complete
 178        its translation.  *EXPP may change; la_post_parser is responsible
 179        for releasing its previous contents, if necessary.  If
 180        VOID_CONTEXT_P, then no value is expected from the expression.
 181        If COMPLETING is non-zero, then the expression has been parsed
 182        for completion, not evaluation.  */
 183
 184     void (*la_post_parser) (expression_up *expp, int void_context_p,
 185                             int completing, innermost_block_tracker *tracker);
 186
 187     void (*la_printchar) (int ch, struct type *chtype,
 188                           struct ui_file * stream);
 189
 190     void (*la_printstr) (struct ui_file * stream, struct type *elttype,
 191                          const gdb_byte *string, unsigned int length,
 192                          const char *encoding, int force_ellipses,
 193                          const struct value_print_options *);
 194
 195     void (*la_emitchar) (int ch, struct type *chtype,
 196                          struct ui_file * stream, int quoter);
 197
 198     /* Print a type using syntax appropriate for this language.  */
 199
 200     void (*la_print_type) (struct type *, const char *, struct ui_file *, int,
 201                            int, const struct type_print_options *);
 202
 203     /* Print a typedef using syntax appropriate for this language.
 204        TYPE is the underlying type.  NEW_SYMBOL is the symbol naming
 205        the type.  STREAM is the output stream on which to print.  */
 206
 207     void (*la_print_typedef) (struct type *type, struct symbol *new_symbol,
 208                               struct ui_file *stream);
 209
 210     /* Print a value using syntax appropriate for this language.
 211
 212        TYPE is the type of the sub-object to be printed.
 213
 214        EMBEDDED_OFFSET is the offset into the outermost object of the
 215        sub-object represented by TYPE.  This is the object which this
 216        call should print.  Note that the enclosing type is not
 217        available.
 218
 219        ADDRESS is the address in the inferior of the enclosing object.
 220
 221        STREAM is the stream on which the value is to be printed.
 222
 223        RECURSE is the recursion depth.  It is zero-based.
 224
 225        OPTIONS are the formatting options to be used when
 226        printing.  */
 227
 228     void (*la_val_print) (struct type *type,
 229                           int embedded_offset, CORE_ADDR address,
 230                           struct ui_file *stream, int recurse,
 231                           struct value *val,
 232                           const struct value_print_options *options);
 233
 234     /* Print a top-level value using syntax appropriate for this language.  */
 235
 236     void (*la_value_print) (struct value *, struct ui_file *,
 237                             const struct value_print_options *);
 238
 239     /* Given a symbol VAR, the corresponding block VAR_BLOCK (if any) and a
 240        stack frame id FRAME, read the value of the variable and return (pointer
 241        to a) struct value containing the value.
 242
 243        VAR_BLOCK is needed if there's a possibility for VAR to be outside
 244        FRAME.  This is what happens if FRAME correspond to a nested function
 245        and VAR is defined in the outer function.  If callers know that VAR is
 246        located in FRAME or is global/static, NULL can be passed as VAR_BLOCK.
 247
 248        Throw an error if the variable cannot be found.  */
 249
 250     struct value *(*la_read_var_value) (struct symbol *var,
 251                                         const struct block *var_block,
 252                                         struct frame_info *frame);
 253
 254     /* PC is possibly an unknown languages trampoline.
 255        If that PC falls in a trampoline belonging to this language,
 256        return the address of the first pc in the real function, or 0
 257        if it isn't a language tramp for this language.  */
 258     CORE_ADDR (*skip_trampoline) (struct frame_info *, CORE_ADDR);
 259
 260     /* Now come some hooks for lookup_symbol.  */
 261
 262     /* If this is non-NULL, specifies the name that of the implicit
 263        local variable that refers to the current object instance.  */
 264
 265     const char *la_name_of_this;
 266
 267     /* True if the symbols names should be stored in GDB's data structures
 268        for minimal/partial/full symbols using their linkage (aka mangled)
 269        form; false if the symbol names should be demangled first.
 270
 271        Most languages implement symbol lookup by comparing the demangled
 272        names, in which case it is advantageous to store that information
 273        already demangled, and so would set this field to false.
 274
 275        On the other hand, some languages have opted for doing symbol
 276        lookups by comparing mangled names instead, for reasons usually
 277        specific to the language.  Those languages should set this field
 278        to true.
 279
 280        And finally, other languages such as C or Asm do not have
 281        the concept of mangled vs demangled name, so those languages
 282        should set this field to true as well, to prevent any accidental
 283        demangling through an unrelated language's demangler.  */
 284
 285     const bool la_store_sym_names_in_linkage_form_p;
 286
 287     /* This is a function that lookup_symbol will call when it gets to
 288        the part of symbol lookup where C looks up static and global
 289        variables.  */
 290
 291     struct block_symbol (*la_lookup_symbol_nonlocal)
 292       (const struct language_defn *,
 293        const char *,
 294        const struct block *,
 295        const domain_enum);
 296
 297     /* Find the definition of the type with the given name.  */
 298     struct type *(*la_lookup_transparent_type) (const char *);
 299
 300     /* Return demangled language symbol, or NULL.  */
 301     char *(*la_demangle) (const char *mangled, int options);
 302
 303     /* Demangle a symbol according to this language's rules.  Unlike
 304        la_demangle, this does not take any options.
 305
 306        *DEMANGLED will be set by this function.
 307
 308        If this function returns 0, then *DEMANGLED must always be set
 309        to NULL.
 310
 311        If this function returns 1, the implementation may set this to
 312        a xmalloc'd string holding the demangled form.  However, it is
 313        not required to.  The string, if any, is owned by the caller.
 314
 315        The resulting string should be of the form that will be
 316        installed into a symbol.  */
 317     int (*la_sniff_from_mangled_name) (const char *mangled, char **demangled);
 318
 319     /* Return class name of a mangled method name or NULL.  */
 320     char *(*la_class_name_from_physname) (const char *physname);
 321
 322     /* Table for printing expressions.  */
 323
 324     const struct op_print *la_op_print_tab;
 325
 326     /* Zero if the language has first-class arrays.  True if there are no
 327        array values, and array objects decay to pointers, as in C.  */
 328
 329     char c_style_arrays;
 330
 331     /* Index to use for extracting the first element of a string.  */
 332     char string_lower_bound;
 333
 334     /* The list of characters forming word boundaries.  */
 335     const char *(*la_word_break_characters) (void);
 336
 337     /* Add to the completion tracker all symbols which are possible
 338        completions for TEXT.  WORD is the entire command on which the
 339        completion is being made.  If CODE is TYPE_CODE_UNDEF, then all
 340        symbols should be examined; otherwise, only STRUCT_DOMAIN
 341        symbols whose type has a code of CODE should be matched.  */
 342     void (*la_collect_symbol_completion_matches)
 343       (completion_tracker &tracker,
 344        complete_symbol_mode mode,
 345        symbol_name_match_type match_type,
 346        const char *text,
 347        const char *word,
 348        enum type_code code);
 349
 350     /* The per-architecture (OS/ABI) language information.  */
 351     void (*la_language_arch_info) (struct gdbarch *,
 352                                    struct language_arch_info *);
 353
 354     /* Print the index of an element of an array.  */
 355     void (*la_print_array_index) (struct value *index_value,
 356                                   struct ui_file *stream,
 357                                   const struct value_print_options *options);
 358
 359     /* Return non-zero if TYPE should be passed (and returned) by
 360        reference at the language level.  */
 361     int (*la_pass_by_reference) (struct type *type);
 362
 363     /* Obtain a string from the inferior, storing it in a newly allocated
 364        buffer in BUFFER, which should be freed by the caller.  If the
 365        in- and out-parameter *LENGTH is specified at -1, the string is
 366        read until a null character of the appropriate width is found -
 367        otherwise the string is read to the length of characters specified.
 368        On completion, *LENGTH will hold the size of the string in characters.
 369        If a *LENGTH of -1 was specified it will count only actual
 370        characters, excluding any eventual terminating null character.
 371        Otherwise *LENGTH will include all characters - including any nulls.
 372        CHARSET will hold the encoding used in the string.  */
 373     void (*la_get_string) (struct value *value,
 374                            gdb::unique_xmalloc_ptr<gdb_byte> *buffer,
 375                            int *length, struct type **chartype,
 376                            const char **charset);
 377
 378     /* Return an expression that can be used for a location
 379        watchpoint.  TYPE is a pointer type that points to the memory
 380        to watch, and ADDR is the address of the watched memory.  */
 381     gdb::unique_xmalloc_ptr<char> (*la_watch_location_expression)
 382          (struct type *type, CORE_ADDR addr);
 383
 384     /* Return a pointer to the function that should be used to match a
 385        symbol name against LOOKUP_NAME, according to this language's
 386        rules.  The matching algorithm depends on LOOKUP_NAME.  For
 387        example, on Ada, the matching algorithm depends on the symbol
 388        name (wild/full/verbatim matching), and on whether we're doing
 389        a normal lookup or a completion match lookup.
 390
 391        This field may be NULL, in which case
 392        default_symbol_name_matcher is used to perform the
 393        matching.  */
 394     symbol_name_matcher_ftype *(*la_get_symbol_name_matcher)
 395       (const lookup_name_info &);
 396
 397     /* Find all symbols in the current program space matching NAME in
 398        DOMAIN, according to this language's rules.
 399
 400        The search is done in BLOCK only.
 401        The caller is responsible for iterating up through superblocks
 402        if desired.
 403
 404        For each one, call CALLBACK with the symbol.  If CALLBACK
 405        returns false, the iteration ends at that point.
 406
 407        This field may not be NULL.  If the language does not need any
 408        special processing here, 'iterate_over_symbols' should be
 409        used as the definition.  */
 410     void (*la_iterate_over_symbols)
 411       (const struct block *block, const lookup_name_info &name,
 412        domain_enum domain,
 413        gdb::function_view<symbol_found_callback_ftype> callback);
 414
 415     /* Hash the given symbol search name.  Use
 416        default_search_name_hash if no special treatment is
 417        required.  */
 418     unsigned int (*la_search_name_hash) (const char *name);
 419
 420     /* Various operations on varobj.  */
 421     const struct lang_varobj_ops *la_varobj_ops;
 422
 423     /* If this language allows compilation from the gdb command line,
 424        this method should be non-NULL.  When called it should return
 425        an instance of struct gcc_context appropriate to the language.
 426        When defined this method must never return NULL; instead it
 427        should throw an exception on failure.  The returned compiler
 428        instance is owned by its caller and must be deallocated by
 429        calling its 'destroy' method.  */
 430
 431     compile_instance *(*la_get_compile_instance) (void);
 432
 433     /* This method must be defined if 'la_get_gcc_context' is defined.
 434        If 'la_get_gcc_context' is not defined, then this method is
 435        ignored.
 436
 437        This takes the user-supplied text and returns a new bit of code
 438        to compile.
 439
 440        INST is the compiler instance being used.
 441        INPUT is the user's input text.
 442        GDBARCH is the architecture to use.
 443        EXPR_BLOCK is the block in which the expression is being
 444        parsed.
 445        EXPR_PC is the PC at which the expression is being parsed.  */
 446
 447     std::string (*la_compute_program) (compile_instance *inst,
 448                                        const char *input,
 449                                        struct gdbarch *gdbarch,
 450                                        const struct block *expr_block,
 451                                        CORE_ADDR expr_pc);
 452
 453     /* Add fields above this point, so the magic number is always last.  */
 454     /* Magic number for compat checking.  */
 455
 456     long la_magic;
 457
 458   };
 459
 460 #define LANG_MAGIC      910823L
 461
 462 /* Pointer to the language_defn for our current language.  This pointer
 463    always points to *some* valid struct; it can be used without checking
 464    it for validity.
 465
 466    The current language affects expression parsing and evaluation
 467    (FIXME: it might be cleaner to make the evaluation-related stuff
 468    separate exp_opcodes for each different set of semantics.  We
 469    should at least think this through more clearly with respect to
 470    what happens if the language is changed between parsing and
 471    evaluation) and printing of things like types and arrays.  It does
 472    *not* affect symbol-reading-- each source file in a symbol-file has
 473    its own language and we should keep track of that regardless of the
 474    language when symbols are read.  If we want some manual setting for
 475    the language of symbol files (e.g. detecting when ".c" files are
 476    C++), it should be a separate setting from the current_language.  */
 477
 478 extern const struct language_defn *current_language;
 479
 480 /* Pointer to the language_defn expected by the user, e.g. the language
 481    of main(), or the language we last mentioned in a message, or C.  */
 482
 483 extern const struct language_defn *expected_language;
 484
 485 /* language_mode ==
 486    language_mode_auto:   current_language automatically set upon selection
 487    of scope (e.g. stack frame)
 488    language_mode_manual: current_language set only by user.  */
 489
 490 extern enum language_mode
 491   {
 492     language_mode_auto, language_mode_manual
 493   }
 494 language_mode;
 495
 496 struct type *language_bool_type (const struct language_defn *l,
 497                                  struct gdbarch *gdbarch);
 498
 499 struct type *language_string_char_type (const struct language_defn *l,
 500                                         struct gdbarch *gdbarch);
 501
 502 /* Look up type NAME in language L, and return its definition for architecture
 503    GDBARCH.  Returns NULL if not found.  */
 504
 505 struct type *language_lookup_primitive_type (const struct language_defn *l,
 506                                              struct gdbarch *gdbarch,
 507                                              const char *name);
 508
 509 /* Wrapper around language_lookup_primitive_type to return the
 510    corresponding symbol.  */
 511
 512 struct symbol *
 513   language_lookup_primitive_type_as_symbol (const struct language_defn *l,
 514                                             struct gdbarch *gdbarch,
 515                                             const char *name);
 516
 517 \f
 518 /* These macros define the behaviour of the expression
 519    evaluator.  */
 520
 521 /* Should we range check values against the domain of their type?  */
 522 #define RANGE_CHECK (range_check != range_check_off)
 523
 524 /* "cast" really means conversion.  */
 525 /* FIXME -- should be a setting in language_defn.  */
 526 #define CAST_IS_CONVERSION(LANG) ((LANG)->la_language == language_c  || \
 527                                   (LANG)->la_language == language_cplus || \
 528                                   (LANG)->la_language == language_objc)
 529
 530 extern void language_info (int);
 531
 532 extern enum language set_language (enum language);
 533 \f
 534
 535 /* This page contains functions that return things that are
 536    specific to languages.  Each of these functions is based on
 537    the current setting of working_lang, which the user sets
 538    with the "set language" command.  */
 539
 540 #define LA_PRINT_TYPE(type,varstring,stream,show,level,flags)           \
 541   (current_language->la_print_type(type,varstring,stream,show,level,flags))
 542
 543 #define LA_PRINT_TYPEDEF(type,new_symbol,stream) \
 544   (current_language->la_print_typedef(type,new_symbol,stream))
 545
 546 #define LA_VALUE_PRINT(val,stream,options) \
 547   (current_language->la_value_print(val,stream,options))
 548
 549 #define LA_PRINT_CHAR(ch, type, stream) \
 550   (current_language->la_printchar(ch, type, stream))
 551 #define LA_PRINT_STRING(stream, elttype, string, length, encoding, force_ellipses, options) \
 552   (current_language->la_printstr(stream, elttype, string, length, \
 553                                  encoding, force_ellipses,options))
 554 #define LA_EMIT_CHAR(ch, type, stream, quoter) \
 555   (current_language->la_emitchar(ch, type, stream, quoter))
 556 #define LA_GET_STRING(value, buffer, length, chartype, encoding) \
 557   (current_language->la_get_string(value, buffer, length, chartype, encoding))
 558
 559 #define LA_PRINT_ARRAY_INDEX(index_value, stream, options) \
 560   (current_language->la_print_array_index(index_value, stream, options))
 561
 562 #define LA_ITERATE_OVER_SYMBOLS(BLOCK, NAME, DOMAIN, CALLBACK) \
 563   (current_language->la_iterate_over_symbols (BLOCK, NAME, DOMAIN, CALLBACK))
 564
 565 /* Test a character to decide whether it can be printed in literal form
 566    or needs to be printed in another representation.  For example,
 567    in C the literal form of the character with octal value 141 is 'a'
 568    and the "other representation" is '\141'.  The "other representation"
 569    is program language dependent.  */
 570
 571 #define PRINT_LITERAL_FORM(c)           \
 572   ((c) >= 0x20                          \
 573    && ((c) < 0x7F || (c) >= 0xA0)       \
 574    && (!sevenbit_strings || (c) < 0x80))
 575
 576 /* Type predicates */
 577
 578 extern int pointer_type (struct type *);
 579
 580 /* Error messages */
 581
 582 extern void range_error (const char *, ...) ATTRIBUTE_PRINTF (1, 2);
 583
 584 /* Data:  Does this value represent "truth" to the current language?  */
 585
 586 extern int value_true (struct value *);
 587
 588 /* Misc:  The string representing a particular enum language.  */
 589
 590 extern enum language language_enum (const char *str);
 591
 592 extern const struct language_defn *language_def (enum language);
 593
 594 extern const char *language_str (enum language);
 595
 596 /* Check for a language-specific trampoline.  */
 597
 598 extern CORE_ADDR skip_language_trampoline (struct frame_info *, CORE_ADDR pc);
 599
 600 /* Return demangled language symbol, or NULL.  */
 601 extern char *language_demangle (const struct language_defn *current_language,
 602                                 const char *mangled, int options);
 603
 604 /* A wrapper for la_sniff_from_mangled_name.  The arguments and result
 605    are as for the method.  */
 606
 607 extern int language_sniff_from_mangled_name (const struct language_defn *lang,
 608                                              const char *mangled,
 609                                              char **demangled);
 610
 611 /* Return class name from physname, or NULL.  */
 612 extern char *language_class_name_from_physname (const struct language_defn *,
 613                                                 const char *physname);
 614
 615 /* Splitting strings into words.  */
 616 extern const char *default_word_break_characters (void);
 617
 618 /* Print the index of an array element using the C99 syntax.  */
 619 extern void default_print_array_index (struct value *index_value,
 620                                        struct ui_file *stream,
 621                                        const struct value_print_options *options);
 622
 623 /* Return non-zero if TYPE should be passed (and returned) by
 624    reference at the language level.  */
 625 int language_pass_by_reference (struct type *type);
 626
 627 /* Return zero; by default, types are passed by value at the language
 628    level.  The target ABI may pass or return some structs by reference
 629    independent of this.  */
 630 int default_pass_by_reference (struct type *type);
 631
 632 /* The default implementation of la_print_typedef.  */
 633 void default_print_typedef (struct type *type, struct symbol *new_symbol,
 634                             struct ui_file *stream);
 635
 636 void default_get_string (struct value *value,
 637                          gdb::unique_xmalloc_ptr<gdb_byte> *buffer,
 638                          int *length, struct type **char_type,
 639                          const char **charset);
 640
 641 /* Default name hashing function.  */
 642
 643 /* Produce an unsigned hash value from SEARCH_NAME that is consistent
 644    with strcmp_iw, strcmp, and, at least on Ada symbols, wild_match.
 645    That is, two identifiers equivalent according to any of those three
 646    comparison operators hash to the same value.  */
 647 extern unsigned int default_search_name_hash (const char *search_name);
 648
 649 void c_get_string (struct value *value,
 650                    gdb::unique_xmalloc_ptr<gdb_byte> *buffer,
 651                    int *length, struct type **char_type,
 652                    const char **charset);
 653
 654 /* The default implementation of la_symbol_name_matcher.  Matches with
 655    strncmp_iw.  */
 656 extern bool default_symbol_name_matcher
 657   (const char *symbol_search_name,
 658    const lookup_name_info &lookup_name,
 659    completion_match_result *comp_match_res);
 660
 661 /* Get LANG's symbol_name_matcher method for LOOKUP_NAME.  Returns
 662    default_symbol_name_matcher if not set.  LANG is used as a hint;
 663    the function may ignore it depending on the current language and
 664    LOOKUP_NAME.  Specifically, if the current language is Ada, this
 665    may return an Ada matcher regardless of LANG.  */
 666 symbol_name_matcher_ftype *get_symbol_name_matcher
 667   (const language_defn *lang, const lookup_name_info &lookup_name);
 668
 669 /* The languages supported by GDB.  */
 670
 671 extern const struct language_defn auto_language_defn;
 672 extern const struct language_defn unknown_language_defn;
 673 extern const struct language_defn minimal_language_defn;
 674
 675 extern const struct language_defn ada_language_defn;
 676 extern const struct language_defn asm_language_defn;
 677 extern const struct language_defn c_language_defn;
 678 extern const struct language_defn cplus_language_defn;
 679 extern const struct language_defn d_language_defn;
 680 extern const struct language_defn f_language_defn;
 681 extern const struct language_defn go_language_defn;
 682 extern const struct language_defn m2_language_defn;
 683 extern const struct language_defn objc_language_defn;
 684 extern const struct language_defn opencl_language_defn;
 685 extern const struct language_defn pascal_language_defn;
 686 extern const struct language_defn rust_language_defn;
 687
 688 /* Save the current language and restore it upon destruction.  */
 689
 690 class scoped_restore_current_language
 691 {
 692 public:
 693
 694   explicit scoped_restore_current_language ()
 695     : m_lang (current_language->la_language)
 696   {
 697   }
 698
 699   ~scoped_restore_current_language ()
 700   {
 701     set_language (m_lang);
 702   }
 703
 704   scoped_restore_current_language (const scoped_restore_current_language &)
 705       = delete;
 706   scoped_restore_current_language &operator=
 707       (const scoped_restore_current_language &) = delete;
 708
 709 private:
 710
 711   enum language m_lang;
 712 };
 713
 714 /* If language_mode is language_mode_auto,
 715    then switch current language to the language of SYM
 716    and restore current language upon destruction.
 717
 718    Else do nothing.  */
 719
 720 class scoped_switch_to_sym_language_if_auto
 721 {
 722 public:
 723
 724   explicit scoped_switch_to_sym_language_if_auto (const struct symbol *sym)
 725   {
 726     if (language_mode == language_mode_auto)
 727       {
 728         m_lang = current_language->la_language;
 729         m_switched = true;
 730         set_language (SYMBOL_LANGUAGE (sym));
 731       }
 732     else
 733       {
 734         m_switched = false;
 735         /* Assign to m_lang to silence a GCC warning.  See
 736            https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80635.  */
 737         m_lang = language_unknown;
 738       }
 739   }
 740
 741   ~scoped_switch_to_sym_language_if_auto ()
 742   {
 743     if (m_switched)
 744       set_language (m_lang);
 745   }
 746
 747   DISABLE_COPY_AND_ASSIGN (scoped_switch_to_sym_language_if_auto);
 748
 749 private:
 750   bool m_switched;
 751   enum language m_lang;
 752 };
 753
 754 #endif /* defined (LANGUAGE_H) */